Safety door latching system for self-cleaning oven having hydraulic thermostat with cam-actuated auxiliary switch

ABSTRACT

A hydraulic oven thermostat for use with a baking oven having a high temperature self-cleaning oven cycle where the thermostat is furnished with an auxiliary switch and camming means interposed between the thermostat knob and the auxiliary switch for coordinating them in both the cooking position and an oven cleaning position as a function of the setting of the thermostat. The auxiliary switch is associated with an oven door latching mechanism, an automatic locking means for the latching mechanism as well as a release means for the locking means to insure that the oven door is locked before the heat-cleaning cycle is initiated as well as insuring that the oven door may not be unlocked until the oven temperature returns to the cooking temperature range.

United States Patent [72] Inventor Christian A. Eff

Louisville, Ky. [21] Appl. No. 847,350 [22] Filed Aug. 4, 1969 [45]Patented Mar. 9, 1971 [73] Assignee General Electric Company [54] SAFETYDOOR LATCHING SYSTEM FOR SELF- CLEANING OVEN HAVING HYDRAULIC THERMOSTATWITH CAM-ACTUATED AUXILIARY SWITCH 12 Claims, 7 Drawing Figs.

[52] U.S.Cl 219/413, 34/45, 219/397 [51] Int. Cl F27d 11/02 [50] FieldofSearch.. 219/395- [56] References Cited UNITED STATES PATENTS2,470,043 5/1949 Monsarrat 34/45 3,121,158 2/1964 l-lurko 219/3973,313,918 4/1967 Barber 219/412 3,317,708 5/1967 Bowling..... 219/4123,301,999 1/1967 Chrisholm. 219/393 3,350,542 10/1967 Getman.....219/412 3,462,584 8/1969 Guy 219/412 Primary Examiner Volodymyr Y.Mayewsky Attorneys-Richard L. Caslin, Harry F. Manbeck, Jr, Joseph B.Forman, Oscar B. Waddell and Frank L. Neuhauser ABSTRACT: A hydraulicoven thermostat for use with a baking oven having a high temperatureself-cleaning oven cycle where the thermostat is furnished with anauxiliary switch and camming means interposed between the thermostatknob and the auxiliary switch for coordinating them in both the cookingPATENTEU MAR 9 1971 SHEET 1 BF 4 R WF f E v. WA N W T Isl R H c PEG? msATTORNEY PATENTEI] MR 9 ISII SHEEI' 2 OF 4 F'IG.3

INVENTOR- CHRST$AN A- EFF Hzs ATTORNEY PATENTEI] m 919m SHEET 3 OF 4 FIGINVENTOR. CHRISTIAN A. EFF

l-us ATTORNEY SAFETY DOOR LATCITWG $YSTEM FOR SELF- QLEANING OVEN HA/ENG HYDRAULIC THERMOSTAT WITH EAM-AQTIJATEID AUXUJIARY SWIITGKIBACKGROUND OF THE INVENTION in most standard baiting ovens a hydraulicthermostat is used for controlling the oven temperatures in the normalcooking temperature range between about 150 F and about 550 F. With theintroduction of the high temperature pyrolytic process for self-cleaningovens as is taught in the patent to Bohdan liurko U.S. Pat. No.3,121,158, the ordinary hydraulic fluid was incapable of withstandingthe high temperatures in the vicinity of 950 F. In recent times, hightemperature fluids have been discovered for use in such hydraulicthermostats in competition with or as a substitute for existing electricthermostats or solid state control thermostats. It is desirable topreserve the resolution of a standard cooking thermostat while expandingthe maximum temperature from about 550 F. to about 950 F. This may bedone with the adoption of an auxiliary switch in-the thermostat housingand camming means interposed between the thermostat knob and theauxiliary switch for coordinating the auxiliary switch with the actionof the thermostat. Special circuit arrangements are also provided toobtain the desired results.

' The principal object of the present invention is to provide ahydraulic oven thermostat with an expanded temperature scale that coversboth normal cooking temperatures and high temperature heat-cleaningtemperature.

A further object of the present invention is to provide a hydraulicthermostat of the class described with an auxiliary switch meansoperated by camming means interposed between the thermostat knob and theauxiliary switch for coordinating them in both a cooking position and acleaning position whereby the thermostat may be calibrated independentlyfor both its cooking temperatures as well as for its cleaningtemperatures without affecting the calibration of the other.

A further object of the present invention is to provide a hydraulicthermostat of the class described with a circuit arrangement whereby thecooking circuits are cancelled and replaced by a cleaning circuit whenthe thermostat, oven timer and oven door latch are closed.

A further object of the present invention is to provide an oventhermostat and circuit arrangement of the class described whereby theoven door latch cannot be opened when the heat cleaning cycle is inoperation until the oven thermostat is reset to a cooking position andthe oven temperature drops into the cooking temperature range belowabout 550 F.

SUMMARY OF THE INVENTION The present invention, in accordance with oneform thereof, relates to a hydraulic thermostat having a housingsupporting an expansible member connected to a remote temperaturesensor. The thermostat has a manually settable knob supporting theexpansible member on its innermost end. The thermostat includesswitching means adapted to be connected in the oven heating circuits,and a snap-acting switch mechanism connected to the switching means andacted upon by the expansible member. An auxiliary switch is combined inthe thermostat housing and it is also adapted to be connected in theoven heating circuits. The auxiliary switch has a cooking position and acleaning position, while the thermostat knob has a variable cookingrange of nearly one revolution over a temperature scale between aboutl50 F. and about 550 F. The thermostat knob also has a clean positionupon continued rotation thereof into the temperature range between about750 F. and about 950 F. The thermostat knob is provided with cammingmeans for governing the actuation of the auxiliary switch so that thecooking and cleaning positions of the auxiliary switch will coincidewith the cooking and cleaning positions of the thermostat knob. Thecamming means in cludes a toggle mechanism for effecting snap-action ofthe auxiliary switch.

BRIEF DESCRIPTION OF THE DRAWINGS My invention will be better understoodfrom the following description taken in conjunction with theaccompanying drawings and its scope will be pointed out in the appendedclaims.

FIG. I is a left, side-elevational view, partly broken away and partlyin section, of a household electric range embodyin the presentinvention.

FIG. 2 is a longitudinal cross-sectional elevational view on an enlargedscale of a hydraulic oven thermostat embodying the present inventiontaken through the center of the housing.

FIG. 3 is a top plane view of the thermostat of FIG. 2 with the left topcover removed and the right top cover partially broken away to show theinterior construction of the thermostat with the thermostat set in thehighest positions for the cooking circuits.

FIG. 4 is a diagrammatic showing of the relationship between thetemperature dial of the thermostat and the position of the auxiliaryswitch mechanism on the interior of the thermostat, with the thermostatset in its lowest cooking position or warm position.

FIG. 5 is a diagrammatic showing similar to that of FIG. 4 just afterswitching from the maximum cooking position or broil" into the cleanposition.

FIG. 6 is a diagrammatic showing, similar to that of FIGS. 4 and 5, withthe then'nostat set in its full clean" position.

FIG. 7 is a schematic wiring diagram of the electrical circuits for theoven of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to a considerationof the drawings, and in particular to FIG. 1, there is shown forillustrative purposes a free-standing electric range 10 having a topcooking surface or cooktop 11 with a plurality of surface heatingelements 12, an oven cavity 13 formed beneath the cooktop by a box-ovenliner l4 and a front-opening drop door 15. The oven liner 14 is suppliedwith two standard resistance heating elements; namely, a lower bakingelement 16 and an upper broiling element 17. A third heating element hasbeen added adjacent the oven door 15 to replenish the heat lost throughand around the door during the heat-cleaning cycle, and thereby retaingenerally uniform oven wall temperatures. This third heater isidentified as a mullion or perimeter heater 18 that is wrapped aroundthe outside of the front of the oven liner; for example, in a mannerthat is taught by the Newell Patent [15. Pat. No. 3,017,488 which isassigned to the General Electric Company, the assignee of the presentinvention. The oven cavity is not shown with oven racks or oven racksupports, but of course they would be necessary in order to provide ameans for supporting food to be cooked within the oven. They are notillustrated here for the sake of simplicity of illustration, becausethey do not form part of the present invention.

The variable control of the surface heating elements 12 is obtained byselector switches 20 which are illustrated as multiple pushbuttonswitches arranged in pairs along the opposite side arms of cooktop II tobe oriented with the particular heating element that is being controlledthereby. In addition, the range is provided with a backsplash 21 that isvertically arranged along the back edge of the cooktop 11 and isprovided with an instrument or control panel 22 in which are mounted thevarious control components of the range and especially of the oven, suchas an oven thermostat 24 embodying the present invention. Other controlcomponents would be an oven selector switch 150, an oven timer 152, aremote-reading meat thermometer, oven indicator and pilot lights,convenience outlets and similar features. Some of these components areillustrated in FIG. 7 as elements in the circuit diagrams.

Other structural features of the range It) include the outer range bodyor cabinet 27 which has an appearance finish on the front, the two sidesand the cooktop ill of the range, while a painted surface is applied onthe back side. This cabinet serves as the superstructure that supportsand encloses the various heating and control components of the range.Sandwiched between the oven liner 16 and the range body or cabinet 27 isan extra thick blanket of thermal insulating material 28 such as fiberglass or the like. The amount of insulation being used has beenincreased over the amount of insulation for standard ovens because ofthe high operating temperatures encountered during the heat-cleaningoperation which will reach a maximum oven wall temperature somewherebetween about 750 F. and about 950 F. Positioned around the blanket ofinsulation 28 are insulation panels or guards 29 which serve to supportthe insulation in place.

During the heat-cleaning operation water vapor, free carbon, soot,carbon monoxide gases and other products of combustion are formed andthese are treated before they are returned to the kitchen atmosphere. Acatalytic smoke eliminator 34 is positioned in an oven vent opening 35in the top wall of the oven liner 14 to serve as an oxidation andexhaust means for the oven. For example, this catalytic smoke eliminatormay be of the type that is taught in the Welch Patent U.S. Pat. No.2,900,483 which is likewise assigned to the assignee of the presentinvention. Such a smoke, odor and vapor eliminating device generallyincludes a heating means in cooperation with a catalytic coating such asa platinum wire screen that becomes heated to a temperature of about1300 F. and tends to consume the smoke, odors and vapors emanating fromthe oven cavity so that the oven exhaust air is treated by removing itsobjectionable constituents in a manner that is best described in thebasic Hurko Patent U.S. Pat. No. 3,12 l ,l58 before it is returned tothe kitchen atmosphere.

It is deemed necessary to provide a latching means for the oven door 15to insure that the door is first closed and cannot be opened while theoven is being operated in a heat-cleaning cycle above normal cookingtemperatures. A suitable door latching mechanism is identified generallyas 37 in FIG. 1, although it is fully taught and claimed in the patentof Clarence Getman U.S. Pat. No. 3,189,375 that is also assigned to theassignee of the present invention. The door latching mechanism includesa manually operable handle lever 33 which extends through an elongatedopening in the front edge of the cooktop 11 in a position just above andparallel to the top edge of the oven door 15. The handle lever 38 hastwo extreme positions, an open or unlocked position and a closed orlocked position. There is a latching bolt 40 which is pivotally mountedwithin the range body and is adapted to extend from the front thereoffor engagement with a slot or keeper (not shown) in the innerside of thedoor 15. The door latching mechanism 37 is provided with an extensionrod 43 which is pivotally connected to the mechanism to move with a backand forth action depending upon the direction of movement of the handlelever 38. This rod 43 has two locking detents at the back of the rangewhere the open position of the handle or latch is illustrated in FIG. 7as a hole 45, and the closed or locking position is represented by theend 46 of the rod. Cooperating with the end of the extension rod 43 isan automatic locking means 48 in the form of a member pivoted about pin49 and it is normally biased in a downward or locking position by meansof a tension spring member 51. Notice that the locking means 48 has afinger 50 for engagement either with the hole 45 or the end 46 of therod depending upon the position of the rod and hence the handle lever38. A solenoid 41 serves as a release means for the automatic lockingmeans 46. The purpose of locking the door latching mechanism 37 in itsopen position is to insure that it cannot be thrown into the closedposition inadvertently, while it is locked in the closed position toinsure that the door cannot be unlocked and the door opened while theoven temperature is above normal cooking temperatures during a hightemperature heat-cleaning operation.

The main purpose for locating the automatic locking means 43 at adistance remote from the door latching mechanism 37 and the front of theoven is to remove the locking mechanism and particularly the releasesolenoid 41 from the high temperature areas of the range and to place itas far as possible away from the oven heat. The energization of thesolenoid causes its armature to pick up and lift the locking means 48 sothe handle lever 38 may be operated.

Turning now to a consideration of the oven thermostat 24 of FIG. 2,represents the hollow housing of the thermostat comprising a recessedbase 56 and a two piece top cover 57 and 53 for closing the base. Thishydraulic oven thermostat or temperature responsive control devicecomprises three main elements within the housing 55; namely, a fluidholding expansible member 60, a snap-action spring mechanism 61 and adouble pole electrical switch mechanism 62.

The recessed base 56 of the housing 55 is a boxlike member of moldedplastic such as phenolic resin or the like insulating material, whilethe two cover members 57 and 58 are thin sheet metal parts. The shape ofthe base 56 is generally rectangular in plan view, as is best seen inFIG. 3. The base is first divided into two sections by a transverse,vertical partition 65. The first section at the right side of thepartition 65 in FIGS. 2 and 3 is adapted to receive the switch mechanism62, while the second section at the left side of the partitionaccommodates the expansible member 60 as well as the auxiliary switch113, as is best seen in the assembly view of FIG. 2. Moreover, the firstsection is further divided into a first upper compartment 67 and asecond lower compartment 68 by means of a horizontal partition 70. It isthis first upper compartment 67 which encompasses the switch mechanism62 and isolates these electrical parts from the remainder of thethermostat interior. Accordingly, the second section of the base forreceiving the expansible member 60 and the auxiliary switch 113 may beconsidered as a third compartment 72. An opening 73 is formed in thelowerportion of the transverse partition 65 in the area between thesecond compartment 68 and the third compartment 72 for receiving aportion of the spring mechanism 61 therethrough, as is best seen in FIG.2. Notice that the cover 58 shown in FIG. 2 is generally of U- shapedformation in side view in that it closes the top opening in the base 56above the first compartment 67, and then it extends down the right sideof the base in the vicinity of the second compartment 68. Some of thegeneral elements of the thermostat of the present invention had beenused before in a thermostat design taught in the patent of Paul R.staples U.S. Pat. No. 3,293,394 which is likewise assigned to theassignee of the present invention.

The third compartment 72 of the base 56 is open at the top, and it isadapted to be closed by the metal cc ver 57 which is fastened over thetop opening thereof and held in place by fastening screws 75.

Attention will now be given to the expansible member 60. It is ahydraulic filled bellows or diaphragm assembly that converts volumetricexpansion or contraction into rectilinear mo tion acting upon theunderlying spring mechanism 61. Into the side of the diaphragm assembly60 is connected a capillary tube 77 of, for example, 2 feet in length.This tube is adapted to extend out of the base 56 so that its free endmay be positioned within the area whose temperature is to be controlled,

such as the oven cooking cavity 13. Provided on the free end of the tubewould be a temperature sensing bulb or probe 78 which is shown locatedin the upper rear portion of the oven liner 14, as is best seen in FIG.1.

It is necessary to be able to adjust the position of the expansiblemember 60 toward and away from the spring mechanism 61 for settingvarious desired temperature levels. The top of the diaphragm assembly isprovided with a vertical pin 80 shown in FIG. 2 which is freely receivedwithin a mating hole 81 in a collar 82 that is fastened on the lower orinnermost end of a threaded adjustment shaft 83. A thermostat knob $6shown in FIGS. 4l-6 is adapted to slip onto the free end of the shaft33. The shaft extends through the cover plate 57 and is adjustably heldtherein by a threaded bushing 84. This bushing has a barrel 85 which isadapted to fit through a close-fitting opening in the cover plate 57. Ashoulder 87 is formed on the lower end of the barrel 35, and thisshoulder together with a speed nut or retaining member 83 holds thebarrel in place in the cover. As shown, the speed nut 88 may he slippedfirst over the shaft and then forced over the barrel 85 until its radialspring fingers 89 engage the bushing in the cover in a semipermanentmanner. The shaft 83 being a threaded member, moves in or out of thehousing as the shaft is turned. dince the diaphragm is confined betweenthe shaft and the spring mechanism til, the diaphragm will stay incontact with the shaft and move therewith.

The diaphragm 151) is prevented from turning when the shaft $3 is turnedby the presence of an inverted U-shaped clip 99 that has its baseportion fixed to the diaphragm and its side portions overlying thespring mechanism 61 in close relationship, as is best seen in H6. 2.

Turning back to a consideration of the first compartment 67 of thethermostat base 56 and the electrical switch mechanism 62 assembledtherein, there are four spaced switch contacts 92 fixed on the topsurface of the horizontal partition 70. These four contacts are arrangedin a transverse rectangular pattern as is best seen in FIG. 2, therebeing a pair of switch contacts located at each side of the firstcompartment 67. This switch mechanism 62 is a double pole, single throwswitch for breaking both sides of the line of a power supply-circuit; asfor example, the supply of energy to the heating elements of an electricoven; elements 16, 17 and 18 of FIG. 1. Each fixed contact 92 isprovided with a perpendicular terminal blade 93 that is adapted toextend down through a suitable slot in the partition 71). The blades 93on the two opposite sides of the thermostat base 56 are then exposed tothe exterior of the base. In other words the second compartment 68 ofthe base is of'narrow width as compared with the width of the firstcompartment 67, or in that matter the width of the third compartment 72.These terminal blades 93 serve as a means for fixing the fixed contacts92 within the base as well as serve as means for making electricalconnection thereto by use of mating electrical connectors (not shown).

In addition to the fixed contacts 92, the switch mechanism b2 includes apair of movable contacts X, and X which are supported by an insulatingcarrier member 95 which is of generally T-shape having a vertical shank96 and overhanging side arms 97. Each side arm 97 supports one of themovable contact members X, and X The lower end of the vertical shank isprovided with a slot 101} so that a connection may be made with thepring mechanism 61.

Now that the expansible member 60 and the switch mechanism 62 has beendescribed, attention is directed to the snap-acting spring mechanism 61which is acted upon by the movement of the expansible member 60 forvarying the position of the switch mechanism 62 according to thedirection and extent of the temperature change experienced by thetemperature sensor or bulb 78 on the end of the capillary tube. Thespring mechanism 61 is in the form of a combined blade and amplitudespring which is best taught by the Staples patent mentioned above. Theblade is formed upwardly to retain a natural upward bowed condition. Theleft end 102 may be identified as the supported end of the blade whilethe right end 1113. may be considered as the free or bistable end of theblade. Between the ends 102 and 103, the blade includes a center leg andright and left parallel side legs as shown in FIG. 3. The blade shouldbe restrained from moving in a horizontal plane and this is accomplishedby interlocking the supported end 162 with the base 56. Looking at FIG.3, the end 1112 of the blade is provided with a pair of oppositelydirected ears 165 which are each adapted to fit snugly into a verticalslot 1% formed in the base. Thus the ears 105 of the blade are droppedinto the vertical slots 1% after the free end 103 of the blade is firstinserted through the opening 73 in the transverse partition 65 and intothe second compartment 68. For calibration purposes a vertical adjustingscrew 1% is fitted up through the bottom wall of the base and is adaptedto be in contact with the supported end N2 of the blade at a point on animaginary line drawn between the supporting cars 1115, as is best seenin FiGS. 2 and 3.

At this stage in the description, the combined blade and amplitudespring 61 is unstable in that it is supported at only one point; namely,on the calibration screw 108. In addition there are two side supports111) provided on the side legs of the blade, which are arranged oppositeto each other in a generally expanded V-shape to provide a dullknife-edge each for bearing upon a support pad 111 of the bottom wall ofthe base 56. Each V-section or side support is arranged opposite eachother or is a mirror image of the other so that the knife edges 110 arelocated in an imaginary transverse line with each other. Thus the blade61 is provided with a three point system; namely, the calibration screw108 at the supported end 102 of the blade and the two knife edges 110,110 at the two sides of the blade.

The center of the expansible member 60 is adapted to bear against thetop portion of the center leg of the blade as at 112. In order to obtainaccurate results, this bearing point is prevented from changing bycreating a small raised embossment on the blade for engagement by theexpansible member 60. Notice that this bearing point 112 is within thetriangular area bounded by the three point support system of thecalibration screw 108 and the two knife edges 110, 110.

What has been described above'with relation to the oven thermostatillustrated in FIGS. 2 and 3 is generally of standard thermostat designas it is generally taught by the before mentioned Staples patent. Theoven thermostat of the present invention has been modified as can beseen in FIGS. 2 and 3 by enlarging the third compartment 72 andinstalling an auxiliary switch 113 therein which is acted upon by acamming mechanism 114 that is interposed between the thermostat shaft 83or knob 86 and the auxiliary switch. The auxiliary switch 113 is asingle pole, double throw switch having a movable contact blade 116mounted in cantilever fashion from a fixed terminal blade 117, and therebeing two fixed contacts 118 and 119 that cooperate with the free end ofthe movable contact 116 depending upon the position of the cam ll 14.

The cam member 114 is a rather large member molded of electricalinsulating material and having a pair of vertical trunnions 122 at thetop and bottom thereof which are fitted into receiving openings in thebottom wall of the base 56 and the top cover 57 so as to be capable oflimited movement about a vertical axis through an angle of about 45. Thecam 114 has opposing faces 124 and 125. Cam face 124 comprises a pair ofcircumferentially spaced notches 126 and 127 for alternate engagementwith a V-shaped cam follower 128 formed adjacent the center of themovable contact blade 116 of the auxiliary switch 113. The second faceof the cam 114 includes an enlarged notch 130 adjacent the top of thecam for engagement by a rotating finger 131 that is fixed to the lowerend of the shaft 83 of the thermostat so as to be movable therewith whenthe thermostat knob 86 is turned. There is a second rotating membersupported by the shaft; namely, a freewheeling stop plate 133 which iscapable of moving independently of the shaft 83. This stop plate has araised abutment 134 which extends upwardly to lie within the same planeas the finger 131 such that the finger may engage the abutment 134 andthereby drive the stop plate ahead of it.

Turning to the diagrammatic showings of FIGS. 4-6, FIG. 4 shows thethermostat turned to its lowest cooking position or warm position, andyou will notice that switch contacts 116 and 118 of the auxiliary switch113 are closed by the action of the cam member 114 and the interrelationbetween the cam follower 128 and the notch 126. Notice the rotatingfinger 131 had previously moved the abutment 134 of the stop plate upagainst the second face 125 of the cam member 114, thereby stoppingfurther rotation in a counterclockwise direction.

The thermostat knob 86 has associated therewith a dial 136 with indiciaprinted around the periphery thereof and extending from a low setting orwarm position of about F. to a maximum cooking temperature of about 550F. Next it shows the highest cooking temperature or broil position. Thisindicia nearly covers the entire periphery of the dial 136. Hence,

to cover such a temperature range it is necessary to turn the knob onthe thermostat through nearly a complete revolution or about 330, as canbe seen by comparing the lowest extreme of the cooking scale of FIG. 4with the highest extreme of the cooking scale of FIG. 5. The thermostatknob is turned clockwise by about 330 to completely cover thetemperature scale from one end to the other. Further rotation of theknob in a clockwise direction first engages the rotating finger 131 inthe slot 131! of the cam 114 and eventually the cam member 114 willshift counterclockwise by about 45 forcing the cam follower 128 out ofthe notch 126 and into the notch 127 thereby allowing the movablecontact blade 116 to snap out of contact with fixed contact 118 and intocontact with fixed contact 1111. in other words there is a type oftoggle switch action here.

After the auxiliary switch 113 has been reset into its clean position ofFIG. 5, the thermostat knob should be turned further to obtain theproper heat cleaning temperature within the oven. This is predeterminedby the turning of the knob 86 in a clockwise direction forcing therotating finger 131 to engage the abutment 13 of the stop plate 133thereby driving it ahead until the abutment 134 engages a calibrationscrew 137 that is adjustably positioned in a sidewall of the base 56 ofthe thermostat housing at which point all further movement in theclockwise direction is halted.

Since the periphery of the dial 136 of the thermostat is substantiallycovered by cooking temperatures, one of the problems to be solved is howto indicate on the thermostat the clean" position. This has been solvedby forming a slit 138 in the edge of the dial. The presence of this slit138 permits the bending of the dial 136 into a flat spiral that has itslowest position at the lowest point of the temperature range and thedial Curves upwardly t the highest point of the temperature rangethereby forming both a horizontal and a vertical slot of about one-eightof an inch. A generally J-shaped indicia strip 139 is fastened at oneend 141) to the thermostat housing or mounting plate of the thermostatwhile the opposite end 141 of the indicia plate 139 is unsupported inthe manner of a cantilever member. This indicia strip 139 is somewhat ofa spring device in that it is normally biased against the underside ofthe dial 136 such that when the thermostat'knob is turned to the end ofthe cooking temperature range the tip 141 of the indicia plate willpenetrate the slot 138 such that continued rotation of the thermostatknob will expose a major part of the indicia plate and thereby covermuch of the indicia of the dial 136 and superimpose the indication cleanto indicate to the housewife the oven thermostat is set to the clean"position.

The electric range 111 of the present invention is furnished with anelectrical service of three-wire Edison source of power; nominally of240 volts, single phase, 60 cycle, AC which is usually available in theaverage residence having adequate wiring. Looking at the schematicdiagram of FIG. 7, this voltage source has a pair of line wires L and Lwith the voltage of 240 volts therebetween, and a grounded neutralconductor N with half voltage or 120 volts measured across any line wireL or L with the neutral conductor N for supplying the electrical load ofthe oven characterized by the three heating elements; the baking element16, the broiling element 17 or the mullion heater 18. The power supplycircuit to the load is furnished with the oven thermostat 24 of thepresent invention so as to govern the temperature within the oven cavity13. The circuit is also supplied with an oven selector switch 151) whichis a multiple position switch for setting up various heating circuits ofthe oven; namely, a bake circuit, a broil circuit or a time-bakingcircuit in conjunction with an oven timer 153. Associated with the oventhermostat 24 as mentioned previously, is an auxiliary switch 113 thatis connected in line L Moreover, there is a latch interlock switch 154.The door latching mechanism 37 and particularly the extension rod 43serves to operate a latch interlock switch 154 and a latch clean switch155. Both of these switches have a normal position and a door latchedposition.

The oven selector switch 150 is provided with a series of line terminalsL T, L, and N, and a series of three load terminals A, B, and C. Theselector switch is provided with a plurality of switch contacts156-1611. These switch contacts 156-160 are labeled with the particularcooking operation that is involved when the contacts are closed. Forexample,

.during a baking operation contacts 156, 158 and 161) are closed. Duringa broiling operation, contacts 156 and 159 are closed. During atime-baking operation, contacts 156, 157 are closed. This oven selectorswitch is bypassed by the latch clean switch during the heat-cleaningcycle. This latch clean switch 155 has but two positions; a normal"position during cooking and a clean position when the oven door latch 37is closed.

The latch clean switch 155 is a multiple circuit switch having twopositions, a normal cooking position and a heat cleaning position. It isnormally biased into the cooking position, and it only switches to itsclean position when the door latching mechanism 37 has been closed. Thislatch clean switch 155 includes switch contacts 162-168. Switch contacts162, 165 and 163 are closed during normal cooking operations while theremaining switch contacts 163, 164, 166 and 167 are closed once the doorlatching mechanism 37 is closed. One side of the latch clean switch 155is provided with five switch terminals DH, while the other side isprovided with four switch terminals J M.

The baking circuit has the bake element 16 operated at full wattageacross lines L and L at 240 volts, while at the same time the broilelement 17 is operated at quarter wattage across lines L and neutralconductor N at 120 volts. The baking circuit may be traced from line Lthrough the auxiliary switch 113 and its contacts 116 and 118, and bylead 260 to thermostat switch contacts X and by lead 201 to lineterminal 1.: of the oven selector switch 150. Then through switchcontacts 156 to load terminal A, then through lead 202 to switchterminal D, and through switch contacts 162 to both the bake element 16and the broil element 17. From the bake element 16, the circuit returnsto line L, through lead 2114, through the latch clean switch by way ofterminal L, switch contacts 165, terminal F and lead 205, and thenthrough the oven selector switch 150 by way of terminal B, switchcontact 155, terminal L and then by lead 206 through thermostat contactX, to line L Then coming 'from the broil element 17, the circuit isthrough lead 207, through the latch 'clean switch 155 by way of terminalM, switch contacts'168, terminal F1, and then by lead 208 through theoven selector switch 150 by way of terminal C, switch contacts 161),terminal N, then by way of lead 209 through neutral conductor N. An ovencycle lamp 1711 is connected in the heating circuits across line L andneutral conductor N by way of leads 211 and 212 where lead 211 isconnected in lead 207 to the broil element 17 while lead 212 isconnected from the lamp 170 back to neutral conductor N. Thus, wheneverthe thermostat switch contact X and X cycle the oven heating elementsOFF and ON, the oven cycle lamp 170 will do likewise.

The time-baking" circuit is somewhat the same as the baking circuitexcept the broil unit 17 is not energized and the oven selector switchcontacts 158 are opened and switch contacts 157 are closed whereby thisportion of the circuit is through terminal T, and then by way of lead214; to the timer switch contacts 152, to thermostat switch contacts Xto line L,.

The broil circuit is a simple circuit where only the broil element 17 isenergized at full wattage across full voltage of 240 volts across linesll. and L This broil circuit may be traced as follows: the circuit isfrom line L through the auxiliary switch contacts 116 and 118, throughthe thermostat contacts X and through oven selector switch contacts 156,and through latch clean switch contacts 162 to the broil element 1'7,and back through latch clean switch contacts 161%, selector switchcontacts 159, and through oven thermostat contacts X to line L,.

Next is the clean circuit where all three heating elements 16, 17 and 18are energized at l20 volts across line L and neutral conductor N. inorder to set up the heat-cleaning circuit there are several preliminaryoperations that must be performed first. As was mentioned previously itis imperative that the oven door be closed beforethe heat-cleaning cycleis initiated, and also that the door remain closed and incapable ofbeing opened while the oven temperatures are above normal cookingtemperatures. There is'a door latch control circuit that is associatedwith the auxiliary switch 113, the latch interlock switch 154 and thesolenoid 41. Remember the door latching mechanism 37 is provided with anautomatic locking means 418 which locks the door latching mechanism inboth its open and its closed positions. Thus, this locking means 48 mustbe unlocked before the handle lever 38 of the door latching mechanism 37may be shifted. included in series circuit with the solenoid dl is anormally open door switch 175 which is closed when the oven door 15 isclosed.

Thus, in order to shift the handle lever 38 from its open to its closedposition it is necessary to set the thermostat 2M0 its clean position,and to close the oven door 15 thereby closing the door switch 175. Thiscompletes a circuit through the solenoid 41 from line 1. through theauxiliary switch 113 and its switch contacts 116 and 119, throughlead216 and2l7 to the latch interlock switch 154 and its switch contacts17-7, and then by lead 218 through the solenoid 41, and lead 219through. the door switch 175 and then lead 220 backto neutral. Once thesolenoid 41 is energized itpicks up the locking means 48 therebyrendering the latching mechanism free to be moved to i tsclosedfposition. Once the latching means 37 reaches its closed position,it actuates the latch interlock switch 154 and closes a setof switchcontacts 179 open in this door latch circuit. The latching means 37 alsoclean position that there is a circuit through a cooling fan motor 181and a clean pilot lamp 182. The purpose of the cooling fan is to blowairaround the outside of the insulated of the outside of the range body27.

Modifications of this'invention will occur to those skilled in this art,therefore it is to be understood that this invention is not limited tothe particular embodiments disclosed, but that it is intended to coverall modifications which are within the true spirit and scope of thisinvention as claimed.

Iclaimr I 1. In a high temperatureself-cleaning oven, a temperatureresponsive control device, said device comprising a housing, anexpansible member adjustably mounted through one wall of the housing andfurnished with a remote temperature sensor, said expansible memberexpanding and contracting according to the direction and extent oftemperature change of the said temperature sensor, and manual settablemeans combined with the expansiblemember for selecting a predeterminedcontrol temperature, electrical switching means including a switchactuator in the form of a snap-acting spring mechanism governed by theexpansionand contraction of the expansible member, said switching meansbeing adapted to be connected in a power circuit that governs theheating means for a self-cleaning oven, and an auxiliary switch meansasshifts the latch clean switch 155 intoits clean position closingswitch contacts 163, 164, 166 and 167. The oven timer 152. is set for avariable cleaning cycle from about 1 hourto 3 hours depending upon theamount of oven soil to be removed. The solenoid circuit remains openuntil the oven completesits heat-cleaning cycle and the timer switch 152is opened 'causing the heat to drop toward the normal ovencooking'temperature range. Then the housewife will reset the oventhermostat 24 and set it to one of the cooking positions thereby closingauxiliary switch contacts 116, 118 such that the door latch circuit iscontrolled by the oven thermostat contacts X Then, when the oventemperature reaches the temperature set by the oven thermostat thethermostat contacts X 2 will closethereb'y completing the.door latchcircuit and again energizing the solenoid and permitting the latchleverS to be shiftedfrom its closed to its open position which in turnwill operatethe latch interlock switch 154 and deenergize the solenoid41.

.Thus it will be understood that the thermostat 24 controls theenergization of thesolenoid 41 which in turn controls the housewifesability to close or open the door latching mechanism 37. A modificationwould be to have the locking means 18 only lock the door latching means37 in the closed position of the door latch which is the hightemperature, heatcleaning position. v

The power to the heating elements during the clean cycle may be tracedas follows whereby the latch clean switch 155 bypasses the oven selectorswitch 150 completely. The heating circuit is across line L, and neutralconductor N through thermostat switch contacts X and through the timerswitch 152, and'then by lead 222 to the latch clean switch terminal G,and then branching through both switch contacts 166 and 167 to carry thecircuit through both the bake element 16 and the broil element 17 andthen by way of lead 203 to latch clean switch contacts 16?. In addition,the mullion heater 18 is connected by lead 227 to lead 204 of the bakeelement 16, and then on its other side by lead 223 to latch clean switchcontacts 16d and then through switch terminal E, and back sociated withthe said thermostat housing and adapted to be connected in either a'cookinig circuit or an oven door locking control circuit, whereby thetemperature responsivecontrol device has a variable"bake"'positionbetween about 150 F. and about 550 F. and a fixed clean positionsomewhere between about 750 F. and about 950 F., the variable bake"position being for. substantially a complete revolution of themanual'settable means with the auxiliary switch being set in a cookingcircuit,-while the fixed clean. position of the control device actuatesthe auxiliary switch into its second oven door locking control circuit,the said manual settable-means including camming means for governing theposition of the auxiliary switch as a function of the position of themanual settable means.

2. In a high temperature self-cleaning oven, a hydraulic thermostatcomprising a housing supporting an expansible member with a remotetemperature sensor, a manual settable shaft extending through onewall ofthe housing and engaging the expansible member on its innermost end,thermostat switching means adapted to be connected in the oven heatingcircuits, a snap-acting switching mechanism connected to the switchingmeans and acted upon by .the expansible member, and auxiliary switchmeans combined with the thermostat housing and adapted to be connectedin the-oven heating circuits saidauxiliary switch means having a cookingposition through the smoke eliminator 34 by means of leads 224 and and acleaning position, the thermostat shaft having-a variable cooking rangeof about one revolution over a temperature scale between about F. andabout 550 F., the thermostat shaft also having a clean position uponcontinued rotation thereof within the temperature scale above about 750F., the thermostat shaft having camming means for governing theactuation of the auxiliary switch means so that the cooking and cleanpositions of the auxiliary switch means will coincide with the cookingand clean positions of the thermostat shaft, said camming meansincluding a mechanism for effecting snap-action of the auxiliary switchmeans.

3. In a high temperature self-cleaning oven, a hydraulic thermostat asrecited in claim 2 wherein the said camming means includes a rotatablefinger mounted on the thermostat shaft and a rotatable cam supported bythe housing and engageable by the said finger to actuate said auxiliaryswitch in the transition of both the thermostat and the auxiliary switchbetween the cooking and the clean" positions, the auxiliary switchincluding a movable spring contact member biased against the said camand movable thereby.

4. In a high temperature self-cleaning oven, a hydraulic thermostat asrecited inclaim 3 wherein the thermostat knob is furnished with a dialthat includes the cooking temperatures marked thereon, the dialincluding an opening at the top of the cooking temperature scale, thethermostat housing supporting an arcuate cantilever, clean" indiciablade which underlies the dial and is adapted to protrude through thesaid opening and overlie a portion of the dial when the thermostat knobis turned to its clean" position.

5. In a self-cleaning oven comprising an insulated cabinet supplied withan oven liner and an access door to form an oven cooking cavity,electrical heating means for saidoven cavity, a circuit network adaptedto connect the heating means to an electrical power supply, a manualselector switch means for the circuit network to effect cookingoperations having normal cooking temperatures between about 150 F. andabout 550 F and door latching means movable between open and closedpositions for holding the door closed during a heat-cleaning cycle whenthe oven temperatures are above the normal cooking temperatures forremoving food soils lodged on the walls of the oven cavity, and lockingmeans and a latch interlock switch means operated when the door latchingmeans is closed for deactivating the release means whenever theheat-cleaning cycle is initiated, the invention comprising a door latchclean switch for bypassing the manual selector switch when the latch isclosed,'a manually settable oven thermostat having switch contact meansin the circuit network which are closed when the oven temperature isbelow the temperature preset on the thermostat and which contact meansare opened when the oven temperature reaches the said presettemperature, said thermostat having a temperature scale which covers thefull range of coking and heat-cleaning temperatures, and an auxiliaryswitch combined with the thermostat and connected in the circuit networkto have a cooking position and a clean" position, and camming meansinterposed between the thermostat and the auxiliary switch forcoordinating them in the cooking position and in the clean position,whereby the thermostat must be reset to a cooking position and the oventemperature must drop into the cooking temperature range before the saidelectroresponsive release means is energized to unlock the door latchingmeans.

6. In a self-cleaning oven as recited in claim wherein the said manuallysettable thermostat has a knob with a variable cooking range of aboutone revolution over a temperature scale between about 150 F. and about550 F., the thermostat knob also having a clean position upon continuedrotation thereof to reach a maximum temperature setting of about 950 F.,the said camming means being associated with the thermostat knob andincluding a toggle mechanism for effecting snapaction of the auxiliaryswitch means.

7. In a self-cleaning oven as recited in claim 6 wherein the saidcamming means includes a rotatable finger mounted to the thermostat knoband a rotatable cam that is engageable by the said finger in thetransition of both the thermostat and the auxiliary switch between thecooking and the clean" positions, the auxiliary switch including amovable spring contact member pressed against the said tumbler andmovable thereby.

8. In a self-cleaning oven as recited in claim 7 wherein the thermostatknob is furnished with a dial that indicates the range of cookingtemperatures, the dial including an opening at the top of the cookingtemperature scale, the thermostat including a housing that supports anarcuate cantilever clean indicia indicator which underlies the dial andis adapted to protrude through the said opening and overlie a portion ofthe dial when the thermostat knob is turned to its clean" position.

9. A self-cleaning oven comprising walls defining an oven cavity, onewall of the cavity including a door for gaining access thereto, a sourceof electric power supply, a first baking circuit adapted to be completedto said power source, a second broiling circuit adapted to be completedto said power source, and a third clean" circuit adapted to be completedto said power source, a manual selector switch having an OFF position, abake position and a broil position, said manual selector switch in itsOFF position interrupting both of said positions, said selector switchin its bake position preparing said first bakig" circuit, said selectorswitch in its broil position preparing aid second broiling circuit, anadjustable oven thermostat having a variable bake" position, a fixedbroil" position and a "clean" position, said thermostat in its variablebake" position correspondingly presetting a variable bake temperaturefor said cooking cavity in the normal cooking temperature rangeextending from about F. to about 550 F., said thermostat in its broilposition correspondingly presetting a broil temperature substantiallynear 550 F said thermostat in its clean position presetting agivenheat-cleaning temperature for said cooking cavity in thetemperature range above about 750 F., door latching means movablebetween open and closed positions for holding the door closed during theheatcleaning operation, locking means for locking the door lathingmeans, an electroresponsive means for releasing the locking means, and alatch interlock switch means having a first open latch position and asecond closed latch position, the thermostat including an auxiliaryswitch means having a first cooking switch position in series with thethermostat and selector switch means and a second cleaning" switchposition to be in circuit with the first open latch position of thelatch interlock switch means and the electroresponsive means when thedoor latching means is in an open position, said electroresponsive meansbeing in circuit with the second closed position of the latch interlockswitch and the thermostat and first cooking position of the auxiliaryswitch means.

10. In a high temperature oven comprising walls defining an oven cavity,one wall of the cavity including a door for gaining access thereto,heating means for supplying heat to the oven cavity for normal cookingtemperatures between about 150 F. and 550 F and a self-cleaning ovencycle with a maximum temperature above about 750 F., door latching meansmovable between an open and a closed position for holding the doorclosed during a high temperature operation above normal cookingtemperatures, locking means for locking the door latching means in itsclosed position, and electroresponsive means for releasing the saidlocking means; the improvement comprising a manual control thermostathaving thermally controlled switch contact means for governing powerdelivered to the heating means and auxiliary switch contact meanssettable into a cooking or a high temperature position as a function ofthe setting of the thermostat into a cooking or a high temperatureposition respectively, a latch interlock switch means having anunlatched and a latched position governed by the position of the doorlatching means, and circuit means including said thermostat and saidlatch interlock switch for controlling the energization of saidelectroresponsive means thereby to allow latching and unlatching of saiddoor, said circuit means having a first circuit actuated through saidauxiliary switch contact means when said thermostat is set to the hightemperature position to allow latching of the door, and a second circuitactuated through said auxiliary switch contact means and said thermallycontrolled switch contact means to allow unlatching of the door, saidsecond circuit being closed only when said thermostat is reset into acooking temperature position and the temperature in the oven cavityreturns to the cooking temperature setting of the thermostat thereby toprevent opening of the door during high temperature operations.

11. In a high temperature oven comprising walls defining an oven cavity,one wall of the cavity including a door for gaining access thereto,heating means for supplying heat to the oven cavity for normal cookingtemperatures between about 150 F. and 550 F. and a self-cleaning ovencycle with a maximum temperature above about 750 F., door latching meansmovable between an open and a closed position for holding the doorclosed during a high temperature operation above normal cookingtemperatures, locking means for locking the door latching means in itsclosed position, and electroresponsive means for releasing the saidlocking means; the improvement comprising a manual control thermostathaving thermally controlled switch contact means for governing powerdelivered to the heating means and auxiliary switch contact meanssettable into a cooking or a high temperature position as a function ofthe setting of the thermostat into a cooking or a high tempera tureposition respectively, a latch interlock switch means having anunlatched and a latched position governed by the position of the doorlatching means, and circuit means including said thermostat and saidlatch interlock switch for controlling the energization of saidelectroresponsive means to prevent opening of the door when the ovencavity is in a high temperature mode, said circuit means incorporatingboth the auxiliary switch contact means and the thermally controlledswitch contact means of said thermostat and being arranged to disable.for governing variable heating rates of the said heating means duringcooking, and a latch clean switch having a first normal cooking positionin series with the oven selector switch and a second clean position thatis set when the door latching means is closed for bypassing the saidoven selector switch and setting up a high temperature heating circuit.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,569,670 Dated March 9, 1971 It is certified that error appears in theabove-identified pater and that said Letters Patent are hereby correctedas shown below:

Column 10, line 51, cancel "cuits" and insert cuit (Please note that thedesignation of the line numbers located in the space between Columns 9and 10 do not correspond to the actual lines beside which they arepositioned. Column 11, line 19, after "means" insert for locking thedoor latching means in its closed posi tion, electroresponsive releasemeans for the said lockin means, Column 12, line 3, cancel "bakig" andinsert baking Column 12, line 4, cancel 'aid" and insert said Column 12,line 17, cancel "lathing" and inse latching Signed and sealed this 1 Tthday of August 1 971 (SEAL) Attest:

EDWARD I LFLETCHELJR. WILLIAM E. SCHUYLER, JR. Attesting OfficerCommissioner of Patents FORM PO-1050 (IO-69)

1. In a high temperature self-cleaning oven, a temperature responsivecontrol device, said device comprising a housing, an expansible memberadjustably mounted through one wall of the housing and furnished with aremote temperature sensor, said expansible member expanding andcontracting according to the direction and extent of temperature changeof the said temperature sensor, and manual settable means combined withthe expansible member for selecting a predetermined control temperature,electrical switching means including a switch actuator in the form of asnap-acting spring mechanism governed by the expansion and contractionof the expansible member, said switching means being adapted to beconnected in a power circuit that governs the heating means for aself-cleaning oven, and an auxiliary switch means associated with thesaid thermostat housing and adapted to be connected in either a cookingcircuit or an oven door locking control circuit, whereby the temperatureresponsive control device has a variable ''''bake'''' position betweenabout 150* F. and about 550* F. and a fixed ''''clean'''' positionsomewhere between about 750* F. and about 950* F., the variable''''bake'''' position being for substantially a complete revolution ofthe manual settable means with the auxiliary switch being set in acooking circuit, while the fixed ''''clean'''' position of the controldevice actuates the auxiliary switch into its second oven door lockingcontrol circuit, the said manual settable means including camming meansfor governing the position of the auxiliary switch as a function of theposition of the manual settable means.
 2. In a high temperatureself-cleaning oven, a hydraulic thermostat comprising a housingsupporting an expansible member with a remote temperature sensor, amanual settable shaft extending through one wall of the housing andengaging the expansible member on its innermost end, thermostatswitching means adapted to be connected in the oven heating circuits, asnap-acting switching mechanism connected to the switching means andacted upon by the expansible member, and auxiliary switch means combinedwith the thermostat housing and adapted to be connected in the ovenheating circuits, said auxiliary switch means having a cooking positionand a cleaning position, the thermostat shaft having a variable cookingrange of about one revolution over a temperature scale between about150* F. and about 550* F., the thermostat shaft also having a''''clean'''' position upon continued rotation thereof within thetemperature scale above about 750* F., the thermostat shaft havingcamming means for governing the actuation of the auxiliary switch meansso that the cooking and ''''clean'''' positions of the auxiliary switchmeans will coincide with the cooking and ''''clean'''' positions of thethermostat shaft, said camming means including a mechanism for effectingsnap-action of the auxiliary switch means.
 3. In a High temperatureself-cleaning oven, a hydraulic thermostat as recited in claim 2 whereinthe said camming means includes a rotatable finger mounted on thethermostat shaft and a rotatable cam supported by the housing andengageable by the said finger to actuate said auxiliary switch in thetransition of both the thermostat and the auxiliary switch between thecooking and the ''''clean'''' positions, the auxiliary switch includinga movable spring contact member biased against the said cam and movablethereby.
 4. In a high temperature self-cleaning oven, a hydraulicthermostat as recited in claim 3 wherein the thermostat knob isfurnished with a dial that includes the cooking temperatures markedthereon, the dial including an opening at the top of the cookingtemperature scale, the thermostat housing supporting an arcuatecantilever, ''''clean'''' indicia blade which underlies the dial and isadapted to protrude through the said opening and overlie a portion ofthe dial when the thermostat knob is turned to its ''''clean''''position.
 5. In a self-cleaning oven comprising an insulated cabinetsupplied with an oven liner and an access door to form an oven cookingcavity, electrical heating means for said oven cavity, a circuit networkadapted to connect the heating means to an electrical power supply, amanual selector switch means for the circuit network to effect cookingoperations having normal cooking temperatures between about 150* F. andabout 550* F., and door latching means movable between open and closedpositions for holding the door closed during a heat-cleaning cycle whenthe oven temperatures are above the normal cooking temperatures forremoving food soils lodged on the walls of the oven cavity, and lockingmeans and a latch interlock switch means operated when the door latchingmeans is closed for deactivating the release means whenever theheat-cleaning cycle is initiated, the invention comprising a door latch''''clean'''' switch for bypassing the manual selector switch when thelatch is closed, a manually settable oven thermostat having switchcontact means in the circuit network which are closed when the oventemperature is below the temperature preset on the thermostat and whichcontact means are opened when the oven temperature reaches the saidpreset temperature, said thermostat having a temperature scale whichcovers the full range of coking and heat-cleaning temperatures, and anauxiliary switch combined with the thermostat and connected in thecircuit network to have a cooking position and a ''''clean'''' position,and camming means interposed between the thermostat and the auxiliaryswitch for coordinating them in the cooking position and in the''''clean'''' position, whereby the thermostat must be reset to acooking position and the oven temperature must drop into the cookingtemperature range before the said electroresponsive release means isenergized to unlock the door latching means.
 6. In a self-cleaning ovenas recited in claim 5 wherein the said manually settable thermostat hasa knob with a variable cooking range of about one revolution over atemperature scale between about 150* F. and about 550* F., thethermostat knob also having a ''''clean'''' position upon continuedrotation thereof to reach a maximum temperature setting of about 950*F., the said camming means being associated with the thermostat knob andincluding a toggle mechanism for effecting snap-action of the auxiliaryswitch means.
 7. In a self-cleaning oven as recited in claim 6 whereinthe said camming means includes a rotatable finger mounted to thethermostat knob and a rotatable cam that is engageable by the saidfinger in the transition of both the thermostat and the auxiliary switchbetween the cooking and the ''''clean'''' positions, the auxiliaryswitch including a movable spring contact member pressed against thesaid tumbler and movable thereby.
 8. In a self-cleaning oveN as recitedin claim 7 wherein the thermostat knob is furnished with a dial thatindicates the range of cooking temperatures, the dial including anopening at the top of the cooking temperature scale, the thermostatincluding a housing that supports an arcuate cantilever ''''clean''''indicia indicator which underlies the dial and is adapted to protrudethrough the said opening and overlie a portion of the dial when thethermostat knob is turned to its ''''clean'''' position.
 9. Aself-cleaning oven comprising walls defining an oven cavity, one wall ofthe cavity including a door for gaining access thereto, a source ofelectric power supply, a first ''''baking'''' circuit adapted to becompleted to said power source, a second ''''broiling'''' circuitadapted to be completed to said power source, and a third ''''clean''''circuit adapted to be completed to said power source, a manual selectorswitch having an ''''OFF'''' position, a ''''bake'''' position and a''''broil'''' position, said manual selector switch in its ''''OFF''''position interrupting both of said positions, said selector switch inits ''''bake'''' position preparing said first ''''bakig'''' circuit,said selector switch in its ''''broil'''' position preparing aid second''''broiling'''' circuit, an adjustable oven thermostat having avariable ''''bake'''' position, a fixed ''''broil'''' position and a''''clean'''' position, said thermostat in its variable ''''bake''''position correspondingly presetting a variable ''''bake'''' temperaturefor said cooking cavity in the normal cooking temperature rangeextending from about 150* F. to about 550* F., said thermostat in its''''broil'''' position correspondingly presetting a broil temperaturesubstantially near 550* F., said thermostat in its ''''clean''''position presetting a given heat-cleaning temperature for said cookingcavity in the temperature range above about 750* F., door latching meansmovable between open and closed positions for holding the door closedduring the heat-cleaning operation, locking means for locking the doorlathing means, an electroresponsive means for releasing the lockingmeans, and a latch interlock switch means having a first open latchposition and a second closed latch position, the thermostat including anauxiliary switch means having a first cooking switch position in serieswith the thermostat and selector switch means and a second''''cleaning'''' switch position to be in circuit with the first openlatch position of the latch interlock switch means and theelectroresponsive means when the door latching means is in an openposition, said electroresponsive means being in circuit with the secondclosed position of the latch interlock switch and the thermostat andfirst cooking position of the auxiliary switch means.
 10. In a hightemperature oven comprising walls defining an oven cavity, one wall ofthe cavity including a door for gaining access thereto, heating meansfor supplying heat to the oven cavity for normal cooking temperaturesbetween about 150* F. and 550* F. and a self-cleaning oven cycle with amaximum temperature above about 750* F., door latching means movablebetween an open and a closed position for holding the door closed duringa high temperature operation above normal cooking temperatures, lockingmeans for locking the door latching means in its closed position, andelectroresponsive means for releasing the said locking means; theimprovement comprising a manual control thermostat having thermallycontrolled switch contact means for governing power delivered to theheating means and auxiliary switch contact means settable into a cookingor a high temperature position as a function of the setting of thethermostat into a cooking or a high temperature position respectively, alatch interlock switch means having an unlatched and a latched positiongoverned by the position oF the door latching means, and circuit meansincluding said thermostat and said latch interlock switch forcontrolling the energization of said electroresponsive means thereby toallow latching and unlatching of said door, said circuit means having afirst circuit actuated through said auxiliary switch contact means whensaid thermostat is set to the high temperature position to allowlatching of the door, and a second circuit actuated through saidauxiliary switch contact means and said thermally controlled switchcontact means to allow unlatching of the door, said second circuit beingclosed only when said thermostat is reset into a cooking temperatureposition and the temperature in the oven cavity returns to the cookingtemperature setting of the thermostat thereby to prevent opening of thedoor during high temperature operations.
 11. In a high temperature ovencomprising walls defining an oven cavity, one wall of the cavityincluding a door for gaining access thereto, heating means for supplyingheat to the oven cavity for normal cooking temperatures between about150* F. and 550* F. and a self-cleaning oven cycle with a maximumtemperature above about 750* F., door latching means movable between anopen and a closed position for holding the door closed during a hightemperature operation above normal cooking temperatures, locking meansfor locking the door latching means in its closed position, andelectroresponsive means for releasing the said locking means; theimprovement comprising a manual control thermostat having thermallycontrolled switch contact means for governing power delivered to theheating means and auxiliary switch contact means settable into a cookingor a high temperature position as a function of the setting of thethermostat into a cooking or a high temperature position respectively, alatch interlock switch means having an unlatched and a latched positiongoverned by the position of the door latching means, and circuit meansincluding said thermostat and said latch interlock switch forcontrolling the energization of said electroresponsive means to preventopening of the door when the oven cavity is in a high temperature mode,said circuit means incorporating both the auxiliary switch contact meansand the thermally controlled switch contact means of said thermostat andbeing arranged to disable the electroresponsive means after latching ofthe door unless the thermostat is set in its cooking position and thetemperature of the oven cavity returns to the cooking temperaturesetting of the thermostat.
 12. In a high temperature oven as recited inclaim 10 with the addition of circuit means including an oven selectorswitch for governing variable heating rates of the said heating meansduring cooking, and a latch clean switch having a first normal cookingposition in series with the oven selector switch and a second cleanposition that is set when the door latching means is closed forbypassing the said oven selector switch and setting up a hightemperature heating circuit.